Capacitive transducers are widely used for electrostatic sensing of displacement and to create electrostatic forces that produce displacement in MEMS microstructures. These transducers consist of at least two electrodes separated by one or more narrow gaps (typically 1-20 microns). When a voltage difference is applied between the two electrodes, a change in position of the electrodes induces a change in the electrical charge on the electrodes, which is detected by external electronics. Typically, at least one of the electrodes is a movable microstructure whose displacement or velocity indicates some physical quantity to be sensed, such as acceleration, rotation, pressure, etc.
A capacitive transducer can also act as an actuator for a movable microstructure, by producing electrostatic forces on the electrodes when a voltage difference is applied between the electrodes.